Not to be used for navigation. Although these data are of high quality and useful
for planning and modeling purposes, they are not suitable for navigation. For navigation,
please refer to the NOS nautical chart series.

While every effort has been made to ensure that these data are accurate and reliable
within the limits of the current state of the art, NOAA cannot assume liability for
any damages caused by any errors or omissions in the data, nor as a result of the
failure of the data to function on a particular system. NOAA makes no warranty, expressed
or implied, nor does the fact of distribution constitute such a warranty.

1

These data not to be used for navigation. Although these data are of high quality
and useful for planning and modeling purposes, they are not suitable for navigation.
For official navigation products, please refer to the U.S. nautical charts available
from the NOAA Office of Coast Survey: http://www.nauticalcharts.noaa.gov.

Each raw data source was converted into ESRI Arc-compatible formats. The resulting
files were converted and adjusted to predetermined projection (geographic), horizontal
datum (NAD27), and vertical datum (MHW) using the ArcInfo PROJECT command and ArcView
Spatial Analyst MAP CALCULATOR algorithm. An ArcView polyline shapefile was created
to represent the coastline. The coastline is based on USGS hydrographic vectors. The
USGS coastline was compared to high-resolution NGS vector shoreline; no discernible
difference was found between the two datasets. Bathymetric contours and data points
were digitized from raster charts and images. Each dataset was analyzed for quality.
Anomalies were removed; approximately 30 points were removed from NOS hydrographic
survey datasets. Overlapping contours and points were assessed for matching. Bathymetric
data was prioritized by quality and date. Recent surveys superseded older data. A
TIN (Triangulated Irregular Network) was created using bathymetric data and coastline
vectors using ArcView 3D Spatial Analyst. A 0.88-arcsecond grid was created. The grid
was contoured at 1-, and 5-meter contours to compare with the original datasets. Problematics
areas were redone by adding additional contours in areas of low point density. The
bathymetric grid was clipped to requested coordinates. USGS 30-meter DEMs were merged
into a single grid and analyzed for quality. The dataset was compare to hydrographic
and hypsographic contours, as well as USGS, NGS, and COOPs control points. Problematics
areas (airport, grid overlaps) were redone by creating TINs using source data. The
topographic grid was clipped to requested coordinates. The topographic and bathymetric
grids were merged into a single 0.88-arcsecond grid. The 0.88-second grid was compared
to the Yakutat AK 2.66-second grid to ensure continuity and quality. A gridmatching
graphic (yak3_1.jpg) was produced to verify nest matching for modeling efforts. The
final grid was analyzed for blunders, systematic errors, and logical consistency.